‘ 
MINUTE STRUCTURE OF A CEREBELLAR FOLIUM. 475 
most characteristic are the basket-cells, which lie in the deeper part of the layer. In addi- 
tion to numerous dendrites the basket-cell gives off an axon, which runs transversely, as 
regards the long axis of the folium, between the planes of adjacent dendritic arborisations 
of the cells of Purkinje. At first very fine these axons gradually become coarse and 
thick, and at intervals they give off collaterals, which run towards the bodies of the cells of 
Purkinje. Reaching these, they break up into an enormous number of fine terminal 
branches, which enclose the cells of Purkinje, as well as the short non-medullated portions 
of their axons, in a close basket-work of fine filaments. 
The granular layer is, for the most part, composed of large numbers of small 
granule-like bodies closely packed together. Each of these possesses a somewhat large 
nucleus, with a very small amount of surrounding protoplasm. From the cell body three 
or four, or perhaps five, dendrites and one axon proceed. The dendrites are short and 
radiate out from different aspects of the cell body. They end in tufts of claw-like twigs, 
which either embrace or are otherwise in contact with neighbouring granule-cells. The 
whole multitude of granule-cells, therefore, are brought into intimate connexion with 
each other. The axon passes into the molecular layer, in which it ends at a varying 
distance from the surface by dividing into two 
branches. These diverge so sharply from each 
other that they almost form a right angle with 
the parent stem, and they run parallel to the long === 
axis of the folium, threading their way between =< 
the branches of the various dendritic planes of = OnE cay 
the cells of Purkinje and entering into contact — - tf 
association with them. When the great number — a 
of granule-cells is borne in mind, and the fact “--~ 
that each sends an axon into the molecular layer, = 
the important part which these fibres, with their == = 
longitudinal branches, take in building up the = —P=Fypy— 
molecular layer will be understood. They are \nl 
found pervading its entire thickness—from the 
surface down to the bodies of the cells of Purkinje. 
Near the cells of Purkinje a few scattered 
cells are seen in the granular layer of a different N--------- 
kind. These are much larger than the ordinary : 
eranule-cells, and are probably of the nature of f/ 
association cells. They are stellate in form, and 
have numerous long branching dendrites and an py¢, 353.—Secrron THROUGH THE MOLECULAR 
N! 
) 
> 
axon which divides up in the granular layer to AND GRANULAR LAYERS IN THE LonG AXIS 
a singular extent. OF A CEREBELLAR FOLIUM (after Kolliker), 
The white centre of the folium gradually Treated by the Golgi method. 
becomes thinner as it approaches the summit. P. Cell of Purkinje. 
This is due to the fibres which compose it @®. Granule Bes. 
eradually entering the gray matter on the surface. Ni aa aaa ane 
oe 5 tole ee : N!. Axons of granule cells in molecular layer. 
These fibres are of three kinds, viz.: (1) axons 
of the cells of Purkinje; (2) fibres which apparently end in the granular layer; and 
(3) fibres which end in the molecular layer. 
The axons of the cells of Purkinje are medullated fibres which, entering the white 
centre of the folium, form a not inconsiderable part of it. 
The fibres which end in the granular layer are called moss-fibres. This name is 
applied to them because, in the granular layer, they present at certain points moss-like 
thickenings, from which short rough twigs proceed. 
The fibres which proceed into the molecular layer give off few or perhaps no branches 
as they traverse the granular layer. In the deeper part of the molecular layer they break 
up into varicose branches, which twine around the primary and secondary stems of the 
Purkinje dendrites. 
Entering into the constitution of the molecular layer are the following elements: (1) 
dendrites of the cells of Purkinje ; (2) basket-cells and somewhat smaller cells nearer the 
surface ; (3) axons of the granule-cells, with their longitudinally arranged branches ; (4) 
the terminations of certain fibres from the white core of the folium, which end in contact 
with the Purkinje dendrites. 
In the granular layer are found: (1) granule-cells; (2) larger stellate association 
cells ; (3) axons of the cells of Purkinje ; (4) moss-fibres ; (5) fibres traversing this layer, 
to end in the molecular layer. 
